Background edges should be taken at character creation. When taken as part of an advance an in game rationalization or event to link them to the new edge.
Characters have studied or been gifted with other worldly Powers. A more detailed description of each background can be found on the Powers sub-page.
Arcane edges are designed to help those with arcane backgrounds get more use out of their background.
Combat edges will help you survive combat.
Leadership edges grant bonuses to subordinates. These edges apply to subordinates within 5" of the leader.
Social edges help convince people to do what you want.
Professional edges represent years of research and training to gain special abilities. Professional edges should only be taken at character creation, they may be taken later but only when led up to it story wise, the character should be practicing the affected trade during down time or in between adventures.
Weird edges are slightly supernatural.